Add function to cancel running async block-copy call. It will be used
in backup.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 include/block/block-copy.h |  7 +++++++
 block/block-copy.c         | 22 +++++++++++++++++++---
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/include/block/block-copy.h b/include/block/block-copy.h
index d40e691123..370a194d3c 100644
--- a/include/block/block-copy.h
+++ b/include/block/block-copy.h
@@ -67,6 +67,13 @@ BlockCopyCallState *block_copy_async(BlockCopyState *s,
 void block_copy_set_speed(BlockCopyState *s, BlockCopyCallState *call_state,
                           uint64_t speed);
 
+/*
+ * Cancel running block-copy call.
+ * Cancel leaves block-copy state valid: dirty bits are correct and you may use
+ * cancel + <run block_copy with same parameters> to emulate pause/resume.
+ */
+void block_copy_cancel(BlockCopyCallState *call_state);
+
 BdrvDirtyBitmap *block_copy_dirty_bitmap(BlockCopyState *s);
 void block_copy_set_skip_unallocated(BlockCopyState *s, bool skip);
 
diff --git a/block/block-copy.c b/block/block-copy.c
index 851d9c8aaf..b551feb6c2 100644
--- a/block/block-copy.c
+++ b/block/block-copy.c
@@ -44,6 +44,8 @@ typedef struct BlockCopyCallState {
     bool failed;
     bool finished;
     QemuCoSleepState *sleep_state;
+    bool cancelled;
+    Coroutine *canceller;
 
     /* OUT parameters */
     bool error_is_read;
@@ -582,7 +584,7 @@ block_copy_dirty_clusters(BlockCopyCallState *call_state)
     assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
     assert(QEMU_IS_ALIGNED(bytes, s->cluster_size));
 
-    while (bytes && aio_task_pool_status(aio) == 0) {
+    while (bytes && aio_task_pool_status(aio) == 0 && !call_state->cancelled) {
         BlockCopyTask *task;
         int64_t status_bytes;
 
@@ -693,7 +695,7 @@ static int coroutine_fn block_copy_common(BlockCopyCallState *call_state)
     do {
         ret = block_copy_dirty_clusters(call_state);
 
-        if (ret == 0) {
+        if (ret == 0 && !call_state->cancelled) {
             ret = block_copy_wait_one(call_state->s, call_state->offset,
                                       call_state->bytes);
         }
@@ -707,13 +709,18 @@ static int coroutine_fn block_copy_common(BlockCopyCallState *call_state)
          * 2. We have waited for some intersecting block-copy request
          *    It may have failed and produced new dirty bits.
          */
-    } while (ret > 0);
+    } while (ret > 0 && !call_state->cancelled);
 
     if (call_state->cb) {
         call_state->cb(ret, call_state->error_is_read,
                        call_state->s->progress_opaque);
     }
 
+    if (call_state->canceller) {
+        aio_co_wake(call_state->canceller);
+        call_state->canceller = NULL;
+    }
+
     call_state->finished = true;
 
     return ret;
@@ -772,6 +779,15 @@ BlockCopyCallState *block_copy_async(BlockCopyState *s,
 
     return call_state;
 }
+
+void block_copy_cancel(BlockCopyCallState *call_state)
+{
+    call_state->cancelled = true;
+    call_state->canceller = qemu_coroutine_self();
+    block_copy_kick(call_state);
+    qemu_coroutine_yield();
+}
+
 BdrvDirtyBitmap *block_copy_dirty_bitmap(BlockCopyState *s)
 {
     return s->copy_bitmap;
-- 
2.21.0

On 01.06.20 20:11, Vladimir Sementsov-Ogievskiy wrote:
> Add function to cancel running async block-copy call. It will be used
> in backup.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  include/block/block-copy.h |  7 +++++++
>  block/block-copy.c         | 22 +++++++++++++++++++---
>  2 files changed, 26 insertions(+), 3 deletions(-)
> 
> diff --git a/include/block/block-copy.h b/include/block/block-copy.h
> index d40e691123..370a194d3c 100644
> --- a/include/block/block-copy.h
> +++ b/include/block/block-copy.h
> @@ -67,6 +67,13 @@ BlockCopyCallState *block_copy_async(BlockCopyState *s,
>  void block_copy_set_speed(BlockCopyState *s, BlockCopyCallState *call_state,
>                            uint64_t speed);
>  
> +/*
> + * Cancel running block-copy call.
> + * Cancel leaves block-copy state valid: dirty bits are correct and you may use
> + * cancel + <run block_copy with same parameters> to emulate pause/resume.
> + */
> +void block_copy_cancel(BlockCopyCallState *call_state);
> +
>  BdrvDirtyBitmap *block_copy_dirty_bitmap(BlockCopyState *s);
>  void block_copy_set_skip_unallocated(BlockCopyState *s, bool skip);
>  
> diff --git a/block/block-copy.c b/block/block-copy.c
> index 851d9c8aaf..b551feb6c2 100644
> --- a/block/block-copy.c
> +++ b/block/block-copy.c
> @@ -44,6 +44,8 @@ typedef struct BlockCopyCallState {
>      bool failed;
>      bool finished;
>      QemuCoSleepState *sleep_state;
> +    bool cancelled;
> +    Coroutine *canceller;
>  
>      /* OUT parameters */
>      bool error_is_read;
> @@ -582,7 +584,7 @@ block_copy_dirty_clusters(BlockCopyCallState *call_state)
>      assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
>      assert(QEMU_IS_ALIGNED(bytes, s->cluster_size));
>  
> -    while (bytes && aio_task_pool_status(aio) == 0) {
> +    while (bytes && aio_task_pool_status(aio) == 0 && !call_state->cancelled) {
>          BlockCopyTask *task;
>          int64_t status_bytes;
>  
> @@ -693,7 +695,7 @@ static int coroutine_fn block_copy_common(BlockCopyCallState *call_state)
>      do {
>          ret = block_copy_dirty_clusters(call_state);
>  
> -        if (ret == 0) {
> +        if (ret == 0 && !call_state->cancelled) {
>              ret = block_copy_wait_one(call_state->s, call_state->offset,
>                                        call_state->bytes);
>          }
> @@ -707,13 +709,18 @@ static int coroutine_fn block_copy_common(BlockCopyCallState *call_state)
>           * 2. We have waited for some intersecting block-copy request
>           *    It may have failed and produced new dirty bits.
>           */
> -    } while (ret > 0);
> +    } while (ret > 0 && !call_state->cancelled);

Would it be cleaner if block_copy_dirty_cluster() just returned
-ECANCELED?  Or would that pose a problem for its callers or the async
callback?

>      if (call_state->cb) {
>          call_state->cb(ret, call_state->error_is_read,
>                         call_state->s->progress_opaque);
>      }
>  
> +    if (call_state->canceller) {
> +        aio_co_wake(call_state->canceller);
> +        call_state->canceller = NULL;
> +    }
> +
>      call_state->finished = true;
>  
>      return ret;

22.07.2020 14:28, Max Reitz wrote:
> On 01.06.20 20:11, Vladimir Sementsov-Ogievskiy wrote:
>> Add function to cancel running async block-copy call. It will be used
>> in backup.
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> ---
>>   include/block/block-copy.h |  7 +++++++
>>   block/block-copy.c         | 22 +++++++++++++++++++---
>>   2 files changed, 26 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/block/block-copy.h b/include/block/block-copy.h
>> index d40e691123..370a194d3c 100644
>> --- a/include/block/block-copy.h
>> +++ b/include/block/block-copy.h
>> @@ -67,6 +67,13 @@ BlockCopyCallState *block_copy_async(BlockCopyState *s,
>>   void block_copy_set_speed(BlockCopyState *s, BlockCopyCallState *call_state,
>>                             uint64_t speed);
>>   
>> +/*
>> + * Cancel running block-copy call.
>> + * Cancel leaves block-copy state valid: dirty bits are correct and you may use
>> + * cancel + <run block_copy with same parameters> to emulate pause/resume.
>> + */
>> +void block_copy_cancel(BlockCopyCallState *call_state);
>> +
>>   BdrvDirtyBitmap *block_copy_dirty_bitmap(BlockCopyState *s);
>>   void block_copy_set_skip_unallocated(BlockCopyState *s, bool skip);
>>   
>> diff --git a/block/block-copy.c b/block/block-copy.c
>> index 851d9c8aaf..b551feb6c2 100644
>> --- a/block/block-copy.c
>> +++ b/block/block-copy.c
>> @@ -44,6 +44,8 @@ typedef struct BlockCopyCallState {
>>       bool failed;
>>       bool finished;
>>       QemuCoSleepState *sleep_state;
>> +    bool cancelled;
>> +    Coroutine *canceller;
>>   
>>       /* OUT parameters */
>>       bool error_is_read;
>> @@ -582,7 +584,7 @@ block_copy_dirty_clusters(BlockCopyCallState *call_state)
>>       assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
>>       assert(QEMU_IS_ALIGNED(bytes, s->cluster_size));
>>   
>> -    while (bytes && aio_task_pool_status(aio) == 0) {
>> +    while (bytes && aio_task_pool_status(aio) == 0 && !call_state->cancelled) {
>>           BlockCopyTask *task;
>>           int64_t status_bytes;
>>   
>> @@ -693,7 +695,7 @@ static int coroutine_fn block_copy_common(BlockCopyCallState *call_state)
>>       do {
>>           ret = block_copy_dirty_clusters(call_state);
>>   
>> -        if (ret == 0) {
>> +        if (ret == 0 && !call_state->cancelled) {
>>               ret = block_copy_wait_one(call_state->s, call_state->offset,
>>                                         call_state->bytes);
>>           }
>> @@ -707,13 +709,18 @@ static int coroutine_fn block_copy_common(BlockCopyCallState *call_state)
>>            * 2. We have waited for some intersecting block-copy request
>>            *    It may have failed and produced new dirty bits.
>>            */
>> -    } while (ret > 0);
>> +    } while (ret > 0 && !call_state->cancelled);
> 
> Would it be cleaner if block_copy_dirty_cluster() just returned
> -ECANCELED?  Or would that pose a problem for its callers or the async
> callback?
> 

I'd prefer not to merge io ret with block-copy logic: who knows what underlying operations may return.. Can't it be _another_ ECANCELED?
And it would be just a sugar for block_copy_dirty_clusters() call, I'll have to check ->cancelled after block_copy_wait_one() anyway.
Also, for the next version I try to make it more obvious that finished block-copy call is in one of thee states:
  - success
  - failed
  - cancelled

Hmm. Also, cancelled should be OK for copy-on-write operations in filter, it just mean that we don't need to care anymore.

>>       if (call_state->cb) {
>>           call_state->cb(ret, call_state->error_is_read,
>>                          call_state->s->progress_opaque);
>>       }
>>   
>> +    if (call_state->canceller) {
>> +        aio_co_wake(call_state->canceller);
>> +        call_state->canceller = NULL;
>> +    }
>> +
>>       call_state->finished = true;
>>   
>>       return ret;
> 


-- 
Best regards,
Vladimir

22.10.2020 23:50, Vladimir Sementsov-Ogievskiy wrote:
> 22.07.2020 14:28, Max Reitz wrote:
>> On 01.06.20 20:11, Vladimir Sementsov-Ogievskiy wrote:
>>> Add function to cancel running async block-copy call. It will be used
>>> in backup.
>>>
>>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>>> ---
>>>   include/block/block-copy.h |  7 +++++++
>>>   block/block-copy.c         | 22 +++++++++++++++++++---
>>>   2 files changed, 26 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/include/block/block-copy.h b/include/block/block-copy.h
>>> index d40e691123..370a194d3c 100644
>>> --- a/include/block/block-copy.h
>>> +++ b/include/block/block-copy.h
>>> @@ -67,6 +67,13 @@ BlockCopyCallState *block_copy_async(BlockCopyState *s,
>>>   void block_copy_set_speed(BlockCopyState *s, BlockCopyCallState *call_state,
>>>                             uint64_t speed);
>>> +/*
>>> + * Cancel running block-copy call.
>>> + * Cancel leaves block-copy state valid: dirty bits are correct and you may use
>>> + * cancel + <run block_copy with same parameters> to emulate pause/resume.
>>> + */
>>> +void block_copy_cancel(BlockCopyCallState *call_state);
>>> +
>>>   BdrvDirtyBitmap *block_copy_dirty_bitmap(BlockCopyState *s);
>>>   void block_copy_set_skip_unallocated(BlockCopyState *s, bool skip);
>>> diff --git a/block/block-copy.c b/block/block-copy.c
>>> index 851d9c8aaf..b551feb6c2 100644
>>> --- a/block/block-copy.c
>>> +++ b/block/block-copy.c
>>> @@ -44,6 +44,8 @@ typedef struct BlockCopyCallState {
>>>       bool failed;
>>>       bool finished;
>>>       QemuCoSleepState *sleep_state;
>>> +    bool cancelled;
>>> +    Coroutine *canceller;
>>>       /* OUT parameters */
>>>       bool error_is_read;
>>> @@ -582,7 +584,7 @@ block_copy_dirty_clusters(BlockCopyCallState *call_state)
>>>       assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
>>>       assert(QEMU_IS_ALIGNED(bytes, s->cluster_size));
>>> -    while (bytes && aio_task_pool_status(aio) == 0) {
>>> +    while (bytes && aio_task_pool_status(aio) == 0 && !call_state->cancelled) {
>>>           BlockCopyTask *task;
>>>           int64_t status_bytes;
>>> @@ -693,7 +695,7 @@ static int coroutine_fn block_copy_common(BlockCopyCallState *call_state)
>>>       do {
>>>           ret = block_copy_dirty_clusters(call_state);
>>> -        if (ret == 0) {
>>> +        if (ret == 0 && !call_state->cancelled) {
>>>               ret = block_copy_wait_one(call_state->s, call_state->offset,
>>>                                         call_state->bytes);
>>>           }
>>> @@ -707,13 +709,18 @@ static int coroutine_fn block_copy_common(BlockCopyCallState *call_state)
>>>            * 2. We have waited for some intersecting block-copy request
>>>            *    It may have failed and produced new dirty bits.
>>>            */
>>> -    } while (ret > 0);
>>> +    } while (ret > 0 && !call_state->cancelled);
>>
>> Would it be cleaner if block_copy_dirty_cluster() just returned
>> -ECANCELED?  Or would that pose a problem for its callers or the async
>> callback?
>>
> 
> I'd prefer not to merge io ret with block-copy logic: who knows what underlying operations may return.. Can't it be _another_ ECANCELED?
> And it would be just a sugar for block_copy_dirty_clusters() call, I'll have to check ->cancelled after block_copy_wait_one() anyway.
> Also, for the next version I try to make it more obvious that finished block-copy call is in one of thee states:
>   - success
>   - failed
>   - cancelled
> 
> Hmm. Also, cancelled should be OK for copy-on-write operations in filter, it just mean that we don't need to care anymore.

This is unrelated: actually only async block-copy call may be cancelled.

> 
>>>       if (call_state->cb) {
>>>           call_state->cb(ret, call_state->error_is_read,
>>>                          call_state->s->progress_opaque);
>>>       }
>>> +    if (call_state->canceller) {
>>> +        aio_co_wake(call_state->canceller);
>>> +        call_state->canceller = NULL;
>>> +    }
>>> +
>>>       call_state->finished = true;
>>>       return ret;
>>
> 
> 


-- 
Best regards,
Vladimir

On 22.10.20 22:50, Vladimir Sementsov-Ogievskiy wrote:
> 22.07.2020 14:28, Max Reitz wrote:
>> On 01.06.20 20:11, Vladimir Sementsov-Ogievskiy wrote:
>>> Add function to cancel running async block-copy call. It will be used
>>> in backup.
>>>
>>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>>> ---
>>>   include/block/block-copy.h |  7 +++++++
>>>   block/block-copy.c         | 22 +++++++++++++++++++---
>>>   2 files changed, 26 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/include/block/block-copy.h b/include/block/block-copy.h
>>> index d40e691123..370a194d3c 100644
>>> --- a/include/block/block-copy.h
>>> +++ b/include/block/block-copy.h
>>> @@ -67,6 +67,13 @@ BlockCopyCallState
>>> *block_copy_async(BlockCopyState *s,
>>>   void block_copy_set_speed(BlockCopyState *s, BlockCopyCallState
>>> *call_state,
>>>                             uint64_t speed);
>>>   +/*
>>> + * Cancel running block-copy call.
>>> + * Cancel leaves block-copy state valid: dirty bits are correct and
>>> you may use
>>> + * cancel + <run block_copy with same parameters> to emulate
>>> pause/resume.
>>> + */
>>> +void block_copy_cancel(BlockCopyCallState *call_state);
>>> +
>>>   BdrvDirtyBitmap *block_copy_dirty_bitmap(BlockCopyState *s);
>>>   void block_copy_set_skip_unallocated(BlockCopyState *s, bool skip);
>>>   diff --git a/block/block-copy.c b/block/block-copy.c
>>> index 851d9c8aaf..b551feb6c2 100644
>>> --- a/block/block-copy.c
>>> +++ b/block/block-copy.c
>>> @@ -44,6 +44,8 @@ typedef struct BlockCopyCallState {
>>>       bool failed;
>>>       bool finished;
>>>       QemuCoSleepState *sleep_state;
>>> +    bool cancelled;
>>> +    Coroutine *canceller;
>>>         /* OUT parameters */
>>>       bool error_is_read;
>>> @@ -582,7 +584,7 @@ block_copy_dirty_clusters(BlockCopyCallState
>>> *call_state)
>>>       assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
>>>       assert(QEMU_IS_ALIGNED(bytes, s->cluster_size));
>>>   -    while (bytes && aio_task_pool_status(aio) == 0) {
>>> +    while (bytes && aio_task_pool_status(aio) == 0 &&
>>> !call_state->cancelled) {
>>>           BlockCopyTask *task;
>>>           int64_t status_bytes;
>>>   @@ -693,7 +695,7 @@ static int coroutine_fn
>>> block_copy_common(BlockCopyCallState *call_state)
>>>       do {
>>>           ret = block_copy_dirty_clusters(call_state);
>>>   -        if (ret == 0) {
>>> +        if (ret == 0 && !call_state->cancelled) {
>>>               ret = block_copy_wait_one(call_state->s,
>>> call_state->offset,
>>>                                         call_state->bytes);
>>>           }
>>> @@ -707,13 +709,18 @@ static int coroutine_fn
>>> block_copy_common(BlockCopyCallState *call_state)
>>>            * 2. We have waited for some intersecting block-copy request
>>>            *    It may have failed and produced new dirty bits.
>>>            */
>>> -    } while (ret > 0);
>>> +    } while (ret > 0 && !call_state->cancelled);
>>
>> Would it be cleaner if block_copy_dirty_cluster() just returned
>> -ECANCELED?  Or would that pose a problem for its callers or the async
>> callback?
>>
> 
> I'd prefer not to merge io ret with block-copy logic: who knows what
> underlying operations may return.. Can't it be _another_ ECANCELED?
> And it would be just a sugar for block_copy_dirty_clusters() call, I'll
> have to check ->cancelled after block_copy_wait_one() anyway.
> Also, for the next version I try to make it more obvious that finished
> block-copy call is in one of thee states:
>  - success
>  - failed
>  - cancelled

OK.

Max